package com.kk.netty.nio;


import io.netty.util.internal.StringUtil;

import java.nio.ByteBuffer;

import static io.netty.util.internal.MathUtil.isOutOfBounds;
import static io.netty.util.internal.StringUtil.NEWLINE;

public class ByteBufferUtil {
    private static final char[] BYTE2CHAR = new char[256];
    private static final char[] HEXDUMP_TABLE = new char[256 * 4];
    private static final String[] HEXPADDING = new String[16];
    private static final String[] HEXDUMP_ROWPREFIXES = new String[65536 >>> 4];
    private static final String[] BYTE2HEX = new String[256];
    private static final String[] BYTEPADDING = new String[16];

    static {
        final char[] DIGITS = "0123456789abcdef".toCharArray ( );
        for (int i = 0; i < 256; i++) {
            HEXDUMP_TABLE[i << 1] = DIGITS[i >>> 4 & 0x0F];
            HEXDUMP_TABLE[(i << 1) + 1] = DIGITS[i & 0x0F];
        }

        int i;

        // Generate the lookup table for hex dump paddings
        for (i = 0; i < HEXPADDING.length; i++) {
            int padding = HEXPADDING.length - i;
            StringBuilder buf = new StringBuilder (padding * 3);
            for (int j = 0; j < padding; j++) {
                buf.append ("   ");
            }
            HEXPADDING[i] = buf.toString ( );
        }

        // Generate the lookup table for the start-offset header in each row (up to 64KiB).
        for (i = 0; i < HEXDUMP_ROWPREFIXES.length; i++) {
            StringBuilder buf = new StringBuilder (12);
            buf.append (NEWLINE);
            buf.append (Long.toHexString (i << 4 & 0xFFFFFFFFL | 0x100000000L));
            buf.setCharAt (buf.length ( ) - 9, '|');
            buf.append ('|');
            HEXDUMP_ROWPREFIXES[i] = buf.toString ( );
        }

        // Generate the lookup table for byte-to-hex-dump conversion
        for (i = 0; i < BYTE2HEX.length; i++) {
            BYTE2HEX[i] = ' ' + StringUtil.byteToHexStringPadded (i);
        }

        // Generate the lookup table for byte dump paddings
        for (i = 0; i < BYTEPADDING.length; i++) {
            int padding = BYTEPADDING.length - i;
            StringBuilder buf = new StringBuilder (padding);
            for (int j = 0; j < padding; j++) {
                buf.append (' ');
            }
            BYTEPADDING[i] = buf.toString ( );
        }

        // Generate the lookup table for byte-to-char conversion
        for (i = 0; i < BYTE2CHAR.length; i++) {
            if (i <= 0x1f || i >= 0x7f) {
                BYTE2CHAR[i] = '.';
            } else {
                BYTE2CHAR[i] = (char) i;
            }
        }
    }

    /**
     * 打印所有内容
     *
     * @param buffer
     */
    public static void debugAll(ByteBuffer buffer) {
        int oldlimit = buffer.limit ( );
        buffer.limit (buffer.capacity ( ));
        StringBuilder origin = new StringBuilder (256);
        appendPrettyHexDump (origin, buffer, 0, buffer.capacity ( ));
        System.out.println ("+--------+-------------------- all ------------------------+----------------+");
        System.out.printf ("position: [%d], limit: [%d]\n", buffer.position ( ), oldlimit);
        System.out.println (origin);
        buffer.limit (oldlimit);
    }

    /**
     * 打印可读取内容
     *
     * @param buffer
     */
    public static void debugRead(ByteBuffer buffer) {
        StringBuilder builder = new StringBuilder (256);
        appendPrettyHexDump (builder, buffer, buffer.position ( ), buffer.limit ( ) - buffer.position ( ));
        System.out.println ("+--------+-------------------- read -----------------------+----------------+");
        System.out.printf ("position: [%d], limit: [%d]\n", buffer.position ( ), buffer.limit ( ));
        System.out.println (builder);
    }

    private static void appendPrettyHexDump(StringBuilder dump, ByteBuffer buf, int offset, int length) {
        if (isOutOfBounds (offset, length, buf.capacity ( ))) {
            throw new IndexOutOfBoundsException (
                    "expected: " + "0 <= offset(" + offset + ") <= offset + length(" + length
                            + ") <= " + "buf.capacity(" + buf.capacity ( ) + ')');
        }
        if (length == 0) {
            return;
        }
        dump.append (
                "         +-------------------------------------------------+" +
                        NEWLINE + "         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |" +
                        NEWLINE + "+--------+-------------------------------------------------+----------------+");

        final int startIndex = offset;
        final int fullRows = length >>> 4;
        final int remainder = length & 0xF;

        // Dump the rows which have 16 bytes.
        for (int row = 0; row < fullRows; row++) {
            int rowStartIndex = (row << 4) + startIndex;

            // Per-row prefix.
            appendHexDumpRowPrefix (dump, row, rowStartIndex);

            // Hex dump
            int rowEndIndex = rowStartIndex + 16;
            for (int j = rowStartIndex; j < rowEndIndex; j++) {
                dump.append (BYTE2HEX[getUnsignedByte (buf, j)]);
            }
            dump.append (" |");

            // ASCII dump
            for (int j = rowStartIndex; j < rowEndIndex; j++) {
                dump.append (BYTE2CHAR[getUnsignedByte (buf, j)]);
            }
            dump.append ('|');
        }

        // Dump the last row which has less than 16 bytes.
        if (remainder != 0) {
            int rowStartIndex = (fullRows << 4) + startIndex;
            appendHexDumpRowPrefix (dump, fullRows, rowStartIndex);

            // Hex dump
            int rowEndIndex = rowStartIndex + remainder;
            for (int j = rowStartIndex; j < rowEndIndex; j++) {
                dump.append (BYTE2HEX[getUnsignedByte (buf, j)]);
            }
            dump.append (HEXPADDING[remainder]);
            dump.append (" |");

            // Ascii dump
            for (int j = rowStartIndex; j < rowEndIndex; j++) {
                dump.append (BYTE2CHAR[getUnsignedByte (buf, j)]);
            }
            dump.append (BYTEPADDING[remainder]);
            dump.append ('|');
        }

        dump.append (NEWLINE +
                "+--------+-------------------------------------------------+----------------+");
    }

    private static void appendHexDumpRowPrefix(StringBuilder dump, int row, int rowStartIndex) {
        if (row < HEXDUMP_ROWPREFIXES.length) {
            dump.append (HEXDUMP_ROWPREFIXES[row]);
        } else {
            dump.append (NEWLINE);
            dump.append (Long.toHexString (rowStartIndex & 0xFFFFFFFFL | 0x100000000L));
            dump.setCharAt (dump.length ( ) - 9, '|');
            dump.append ('|');
        }
    }

    public static short getUnsignedByte(ByteBuffer buffer, int index) {
        return (short) (buffer.get (index) & 0xFF);
    }
}
